What is Quantum Computing?

I'm trying to wrap my head around the concept of quantum computing. Can you explain it in plain English, and tell me if this is something that's available now, or if it's still in the concept phase?

Is There a Quantum Computer in Your Future?

The overriding imperative of computing is "go faster, get smaller". The number of transistors that can be manufactured on a standard silicon wafer has doubled roughly every two years, as Moore's Law predicts. That means transistors keep growing smaller. The smaller the distance between transistors, the faster computations happen. If Moore's Law continues to be an accurate predictor, then around 2020 or 2030 we should see transistors the size of individual atoms. That's when quantum computing will come to fruition.

Quantum computing is based upon physics completely different from that observed in the electronic devices of today. In today's computing paradigm, a transistor can be in only one of two states called bits - 0 or 1, on or off. But in the realm of quantum computing a transistor can be in a state of 0, 1, or a "superposition" of 0 or 1. And there can be many superpositions. These quantum bits are called "qubits." Physically, qubits are encoded in atoms, photons, ions, or electrons.

Whereas a standard transistor can perform only one operation at a time, a qubit can perform many simultaneously. Therefore a quantum computer containing the same number of transistors as an ordinary computer of today can be a million times faster. A 30-qubit quantum computer could perform as many as 10 teraflops - 10 trillion floating-point operations per second! Today's desktop computers perform gigaflops - billions of operations per second.

So obviously, that's where the interest in quantum computing comes from - speed. A personal computer a million times faster than the one currently on your desk boggles the mind. After all, how fast can you type? But there are applications that would benefit from that type of speed, such as image recognition, cryptography, and other problems that require enormous computing power. Personally, I'd be happy with a computer that's ready to go as soon as you turn it on. I don't anticipate being able to type a million times faster than I already do. J

One problem with quantum computing is that if you observe the quantum state of a qubit, it changes. So scientists must devise an indirect method of determining the state of a qubit. To do this, they are trying to take advantage of another quantum property called "entanglement." At the quantum level, if you apply a force to two particles they become "entangled;" a change in the state of one particle is instantly reflected in the other particle's change to the opposite state. So by observing the state of the second particle, physicists hope to determine the state of the first.

Yes, quantum mechanics is rather confusing. But from a layman's perspective, it's enough to know that quantum computing is based on a new type of transistor that is represented by the changing states of atomic particles. And the promise of quantum computing is a HUGE breakthrough in speed.

Are Quantum Computers Available Today?

There is at least one firm that claims to have created a rudimentary, working quantum computer. Canada-based D-Wave Systems has demonstrated a 16-qubit quantum computer that solved sudoku puzzles and other pattern-matching problems. Some in the scientific community are skeptical about D-Wave's claims, but there is definite progress on the quantum computing front every day.

Quantum computers need at least a few dozen qubits in order to solve real-world problems usefully. It may be several years, even a couple of decades, before a practical quantum computer is put into production. But just as world records fell more rapidly after the first sub-four-minute mile was run, the breakthrough of the first commercial quantum computer will undoubtedly be followed by very rapid increases in quantum computing capabilities; reductions in costs; and shrinkage in size. In a decade or so, we can expect to find old-school transistors and simple on-off bit technology joining analog video tape in the dustbin of technology history.

Do you have something to say about quantum computing? Post your comment of question below...

Most recent comments on "What is Quantum Computing?"

The inventiveness of our computer geniuses is matched only by the cleverness of the terms they come up with.

Bit ... byte ... nibble! Yup.

Bit ... qubit (think of the biblical "cubit")

Of course, there was the "Bit Bucket" of old -- actually a little container where the "holes" of paper tape were collected, rather than letting them fall on the floor. Anyone here remember having to empty the bit bucket?

There are so many, many colorful, often tongue-in-cheek computer terms. But this old codger's brain could only recall those few. Can you think of any? (I guess I'm off-topic Bob. My feelings won't be hurt if this post lands in the bit bucket.)

I have no problems with your explanation about quatum technology. The explanation about the state of a qubit is however not as simple to detect! At present there is a debate going about
this in the community whether the entangled state realy reflect the state of the qubit? We are working on a detection methode but at present it is very crude! As you mentioned it flops at a high speed and one mistake in the program just
collapses the whole thing! The sleitest aberation
is deadly here. Your prognosis of having a desktop
qubit is very optimistic, remember we have very
litle software writen that is hyperthreading,
let alone written in quantum? Astronomy and space
exploration would greatly benefit, but a desktop?
There are other problems with this technology of which I will not mention at this point, you will here about it in the future.

Posted by:
Jason Wallwork
05 Feb 2010

"A 30-qubit quantum computer could perform as many as 10 teraflops - 10 trillion floating-point operations per second! Today's desktop computers perform gigaflops - billions of operations per second.
So obviously, that's where the interest in quantum computing comes from - speed. A personal computer a million times faster than the one currently on your desk boggles the mind."

Isn't a trillion 1000x a billion? Did you mean a petaflop?

Posted by:
JimMe
05 Feb 2010

A friend who worked in Silicon Valley back in the 80s recalled what some were referring to then in computer technology as the "anticipation" theory or the ability of computers to predict (or anticipate) results based on past performance. This is not a new theory....man has been doing this for much of humankind's existence.....but when applied to today's advanced computer "thinking" skills it can predict in milliseconds just ahead of the curve. In the military this can be critical. Posit, for example, a missile which has the ability to adjust to a counter threat BEFORE the threat
takes place by "anticipating" based on past performance - somewhat like a boxer who is already parrying a punch before it is thrown.

If this sounds like science fiction tell that to the wierdos who have already developed machines that can physically respond to thougth processes. The technology exists.

Posted by:
Steven
08 Feb 2010

Everything I do on this computer won't go any faster than I can type, look for things in a quantum computer. 12 years later, my typing and spelling are still bad.
Can someone say "good enough computing" Steven 4 typos were corrected, before sending.

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